I took another trip to the Colonie Toys R Us, ready for another disappointment. I had been looking for these, stopping in once a week or so, since availability was first announced on rec.models.rockets (RMR) in mid-May. We even made a quick pit-stop on our way back from RAMTEC in a Toys R Us near the PA/NJ border to see if they had some, with no luck. Today was to be different, though. They had six starter kits: two Space Shuttle/Saturn V, two SR-71 Blackbird/Tomahawk cruise missile, one UFO/Spacefighter, and one with plain rockets. No motor packs, though. I opted for both a Space Shuttle/Saturn V and a UFO/Spacefighter. I didn't need two launchers, but for the extra motors -- they include eight per starter kit -- and yeah, the rockets are kinda cool looking. :)
I got them home and, after a quick call to rocket buddy Wolf, opened up the UFO/Spacefighter starter kit. There is a four page instruction sheet that explains how to set things up and fly them and a one page troubleshooting supplement. All quite sufficient. One interesting note is the recommendation to fly these models only in winds of 5 or 7 mph or less (depending on which part of the instructions you read).
The launcher is a thermos-like plastic canister, which folds open (much like the panels on the old MPC Pilgrim Observer). The central base forms the launch pad, with internal wiring for the special ignitors, while the panels just look cool, right down to the little fold-up "WARNING - Stand back 15 feet before launching" placards. The bottom of the base is removable and serves as storage for the Quest launch controller. That looks like a black yo-yo or hockey puck and it glows and chirps when you have continuity. It's powered by a fresh 9 volt alkaline battery (remember that).
The launch rod is a tiny 11" long piece of 0.047" music wire. It is placed in one of two positions in the base in relation to the ignitor, depending on the particular rocket. The ignitors look like the old Cox ignitors -- a plastic plug which positively locks into the launcher base, with a thin nichrome (with no pyrogen) for ignition. The model is gently lowered unto the ignitor for flight.
The rockets themselves are pretty cool looking. The UFO is the neatest, measuring a whopping 2.75" in diameter and tipping the scales at 7.7 grams (about 1/4 ounce). It is molded in black plastic with colorful stickers and "Made in China" embossed on the underside (now we know where our advanced technology has been going to :). UFO recovery is the standard featherweight. The Spacefighter is a futuristic little blob, with a fuselage and fins somewhat reminiscent of the Bullpup. It weighs 8.3 grams and is 4 3/8" long. It's black with blue and yellow accents. Its nose separates, revealing a tiny shock cord and 0.5" x 8" aluminized mylar streamer. Some of the other models reportedly use a constrained internal piston, where the nose slides outward and deploys the streamer, but does not separate. Another characteristic technology of these models are motor mounts that lock the motor in place.
Now to the motors, ah yes the motors... You won't believe these little guys. They are 0.25" in diameter and 1.0" long. They feature a one-piece injection-molded plastic casing and nozzle assembly (the nozzle is approximately 0.045" diameter and 0.25" deep -- tiny!). A clay cap covers the ejection charge. Loaded weight is 1.25 grams, propellant weight is 0.4 grams, empty weight is 0.85 grams. NAR Standards & Testing (May/June '99 Sport Rocketry, page 42) rates them as 0.20 Newton-seconds (or, as the Quest packaging refers to it "200 Mil N-sec"), with a burn time of 0.82 seconds and a measured delay time of 1.07 seconds. I can quote you numbers, but you can't appreciate them until you hold the in your hand and see how absolutely positively TEENY WEENY they are!
Enough of the tech inspection, let's get down to flying them! I loaded up the UFO and Spacefighter for flight. The UFO was nominal. The nose on the Spacefighter seemed quite loose, so I shimmed it with a little Scotch tape, and dusted that with talcum powder. I had heard that the mylar streamers were susceptible to heat damage, so I put about 1/4 of a square of Estes wadding into the Spacefighter (it appears to have some sort of ejection baffling built in, but I can't be sure of the details without taking the model apart).
I had forgotten to pick up a battery so I scrounged an old 9 volt from around the house. It lit the continuity light and made the controller chirp, so I figured we were in business. I set things up in my backyard, ready to launch... Until my battery met up with the Quest ignitors -- you really do need a fresh battery. With daylight dimming, we made a quick trip to the local rocket shop (Price Chopper) for a rocket battery, and we were back at the rocket range before sunset.
First up was the Spacefighter. It had a nominal flight to approximately 40 feet, ejected its streamer, and recovered successfully. Post flight examination showed that the wadding had not been ejected and the streamer was scorched almost to the point of separating from the shock cord. Maybe I'll try putting the wadding just behind the streamer next time, instead of butting it against the baffle bulkhead.
Next came the UFO. Reports on RMR said its performance was less than spectacular, and they were right (but it's still a cool model). The UFO roared to a peak altitude of about ten (yes, 10) feet at burnout, then quickly retreated back to earth, ejecting right around "impact". In the process of loading up the UFO, I broke one of the ignitors, trying to tweak it to ensure it didn't short out. It looks like some careful soldering will make it usable again.
As Del Ogren stated on RMR, "F really does equal MA!" He was referring to the performance of the Quest pre-fab models versus some scratchbuilt models (with rolled balsa tubes) he had made for the motors. The Quest literature reports that Micro Maxx can reach altitudes of 200 feet. And they can. Just not in any of the models that Quest sells! They can probably do about one-third of that, tops. It will be most unfortunate if the Micro Maxx line does not sell well due to lackluster performance characteristics. The motors are great for experimenters who build their own models (and companies like Pratt Hobbies and Totally Tubular are planning to offer parts to support these tiny motors). Let's hope they sell well and there are further Micro Maxx releases.
Today's task at hand is to look into the contest potential of these motors. And, what better way than to try one of my favorite events, gliders. George Gassaway has published a photo and plans for a micro glider on his web pages.
Pictures of several Czech micro gliders
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Plan drawing of a Czech micro glider
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This glider was built to use Czech micro motors, motors even a bit smaller than the Quest motors (I have specs for them around here somewhere and will share them if I find them).
My glider was based on the plans, but with a few slight differences. I used medium weight 1/16" balsa for the fuselage, medium weight 1/32" balsa for the wing, and light 1/32" balsa for the tail feathers. The pod was an expanded Totally Tubular T-2 (slit and the fuselage and two 1/32" spacers used to increase the tube diameter to fit the motor) with a nose hacked out of scrap balsa. A small box formed by two pieces of 1/32" balsa approximately 1/16" wide x 1" long in the wing root served as a launch lug. Wing area is a whopping 3.5 square inches (while fifteen or so is typical for a 1/4A B/G). Empty weight is 0.85 grams. Loaded weight is 2.1 grams. Now you're talking...
With a bit of hand tossing, a bit of clay on the tail, it actually looked like it wanted to glide. On to the pad it went, with a custom music wire gantry in the second rod hole, holding an Estes ignitor, wired to a standard Estes controller. You have to be really selective, and look for an ignitor with a very slender tip. My first attempt resulted in a misfire, but I later cleaned up the motor and it should be usable in the future. My second attempt (with a new motor) worked.
The boost was spectacular (sims say the instantaneous acceleration hit about 70 G's!). I picked it up in the sky around burnout. It had pitched up (as expected) and boosted up-range about 100 feet at an altitude of about 50 feet. At ejection, tragedy struck, and it made like a lame duck and fluttered to the ground. I thought the force of the ejection might have snapped the pylon, but it turned out the fuselage had broken just ahead of the stabilizer. I don't know if it was a weak point or if the motor actually impacted the stab at ejection. Flight time was 7.3 seconds. Based on the altitude and glide performance, it probably would have stayed up for 15 seconds or so.
For future flights I plan to launch it at a 30 degree pitch-down angle to counter the pitch up tendencies. I might also adopt the launch lug positioning in George's plans, which would also help this. The hot boost on the model also takes it a bit out of the realm of "backyard rocketry" (and it sure ain't "indoor rocketry"), so I will have to be careful when and where I fly it.
Future gliders will probably be bigger, since I think this model is just too small -- it boosts too fast and is hard to see in boost and glide, and a larger model should be a much more efficient glider. One of the "disadvantages" of the Quest Micro Maxx motors is that they have so little power, models have to be made light and tiny, and everything happens fast!
Rebuilt the glider and reinforced the tail. Added coloring with black and fluorescent yellow magic markers. Some more glide testing revealed that it really doesn't like windy conditions and that it likes a faster than expected glide speed.
In the evening I created a Quest Micro Maxx motor file for RASP and did some sims (I had avoided doing this earlier, for fear the anticipation of flying the models I was sim'ing before the motors were available would be too much for me :).
One thing which Andy Eng had warned of on RMR was the liability of the short one second delay. I didn't think it would be that much a problem, with the low impulse, and the low sustainer thrust. Turns out Andy was right. With the most extreme cases, a minimum-diameter and minimum-mass model would reach 500 feet and coast for up to four seconds! So while these motors will be good for draggy or heavy contest models (ie: gliders or helicopters), altitude or PD/SD events would be a balance between making your model tiny enough to get a good altitude versus the strength required to stand up to a recovery system deployment at up to 100 mph.
While there are some rumors of other Quest Micro Maxx models (even a glider), I don't know if that would include devoting the manufacturing capacity to an alternative delay. It sure would be nice, though, to have a three second delay.
Today was rainy and humid, so I was limited to building. I turned my attention to PD/SD. Considering the delay situation and the undersized glider I built, I think a non-minimum-diameter model might be the way to go. The 10.5mm Apogee micro tubing looks so gigantic next to these motors, though, so I thought Totally Tubular's T-3 (0.375" diameter) was a good compromise.
I made a small model with 4.5" of T-3 and a hand-turned 0.75" balsa nose. Fins are hard 1/32" balsa clipped deltas with a 0.625" root, 0.375" tip, and 0.75" semi-span. The motor mount is two T-2/3 rings, peeled to fit the motor and installed 0.75" apart (measured outside to outside). The motor has several wraps of 1/8" masking tape at the top, it is installed from the top, then more 1/8" masking tape is wrapped around the protruding nozzle to lock it in place. The shock cord is approximately 18" of fifteen pound Kevlar, with a 2.5" x 26" 0.75 mil mylar streamer attached. Two small launch lugs of Plastruct tubing (3/32" OD, which just barely fit the rod) were used. The empty model is about 1.85 grams, the streamer is about 0.9 grams. Loaded weight should be a little over 4 grams.
Then I spent a couple hours typing this up... :)
Got some good weather today, so it was time to fly. Since the models I planned to fly were non-stock (and wouldn't fit the Quest launcher/ignitor scheme), I wanted to use different ignitors. After examining some more Estes ignitors, it seems the ones I found that would fit the Quest nozzles were far more the exception than the rule. So I pulled out some older Apogee micro ignitors -- these have a small enough head to fit into the Quest nozzles, or the pyrogen can be shaved down to fit. A stock toothpick (without the end removed, as done for Apogee) fit the nozzle snugly. These ignitors were used for the three flights below. They were lit with an Estes launch controller (6v alkaline), but you have to be careful to attach the clips close to the motor (to reduce the overall resistance).
First up was the B/G. To counter its pitch-up tendencies, it was launched at a 15-20 degree pitch-down angle. The boost seemed fairly vertical. Not that you could really tell. This model is so tiny and disappears so quick, the SOP is to look up, listen for the ejection charge, and then look where the sound was. Unfortunately, the ejection charge again broke the fuselage, this time at the front pylon. It occurred at a significantly higher altitude, though, (maybe 150 feet?), so the flight (flutter) time was 24.6 seconds. I was very lucky to find the nose section (only about 1" long). I hope I get this right before I run out of motors. ;) I guess I need a bit more than medium weight 1/16" balsa for this fuselage.
Second flight was the SD model. Post-flight measurements put the empty model mass at 2.75 grams, wadding (1/2 square Estes wadding in four pieces) and tape (to mount motor) at 0.25 grams, and the motor at 1.25 grams, for a lift-off mass of 4.25 grams. I had to use the opposite end of the launch rod as the tight lugs would bind on the painted portion of the launch rod. Lift-off was nominal, with the model reaching approximately 100 feet by ejection. It didn't seem like the delay was significantly short for the model. The streamer ejected, but did not unfurl. Total flight time was 8.6 seconds. Later examination suggested that masking tape used to reinforce the streamer mount (a common practice on my larger models) was sufficiently stiff to prevent the streamer from unfurling. This tape was removed. I had also wrapped the shock cord around the streamer 2 or 3 times, but this did not appear to be a factor (although I did not repeat that for the next flight).
A second flight attempt was made. The boost was similar, perhaps with a bit of tip-off. This time the streamer deployed promptly and fully. A really pretty flight, which took some body english to keep out of my neighbor's tree. :) Drift was minimal and I was able to catch the model. Flight time was 22.4 seconds. I don't believe this was thermal-aided, although I cannot be sure at this point. A great flight to top off a less-than-stellar day of flying.
I made a couple of flights shortly before dark tonight. The first was to test the SD model again in what should be non-thermal conditions. Lift-off mass was 4.4 grams. It was flown with an Apogee micro ignitor, off the Quest rod & pad, with an Estes launch controller. The launch and boost was good, to 100 feet or more, and (again) didn't seem to have a lot of velocity remaining at ejection. Streamer deployment was good, and the model drifted ever so slightly (3 or so fps) and managed to snag itself about 40 feet up in a maple tree in my neighbor's yard. The hazards of "backyard rocketry"... :( Flight time was 17.3 seconds, which (considering the altitude "lost" by the tree-shortened flight) would indicate that the previous time (22 sec) was representative and not thermal-aided. I'll have to wait until we get a little wind here, which may dislodge the model.
Flight two was a dual purpose test. It was the flight of a small Apogee micro-engine helicopter duration model. First, it was a test of a 1/8A HD model. HD is one of the more difficult/complex contest models, and it was a challenge to see if it could be flown with so little impulse. A second aspect of this flight was whether 1/4A contest models could be flown with the new motors. Contest models are often highly-optimized, and it is not trivial to move one or two total impulse (letter) classes and still have the model function nominally. In this case, it's a bit like taking a model designed for an Estes D12 and flying it with an Apogee B7 (since the Micro Maxx has about one third the total impulse of 1/4A motors). Anyways...
The model is a mini/micro-Roseroc, designed for 1/4A and 1/2A HD. The nose is about 0.55" diameter, the rotors are 0.5" x 6.5" with 0.5" x 6.0" flaps, and the motor mount is 10.5mm. Normally flown from a tower, a one inch long 1/8" diameter launch lug was added to one fin. Empty weight was 5.9 grams, plus 0.7 grams of tie-down thread and masking tape (the motor was simply taped with 1/2" masking tape to fit the tube), plus a nominal 1.25 grams for a fresh engine, and the gross lift-off mass was 7.85 grams. The model was launched from a 1/8" x 18" Estes rod & pad with the Estes launch controller and a Quest ignitor. The ignitor was inserted into the nozzle and allowed to hang free. This led to the ignitor getting tweaked around by the micro clips -- a less than ideal situation, but I got away with it this time. You really want something on the launch rod to hold the Quest ignitor firmly (no doubt why the clothespin was invented...).
The boost was "majestic" (ie: underpowered :), with apogee around 25 feet and ejection spot on. The rotors quickly deployed and the model quickly spun up and descended in a stable autorotation. Flight time was a less-than-impressive-sounding 8.4 seconds, but it featured a solid 5-6 seconds of autorotation. If I recall correctly, a typical 1/4A time with this model might be 20-30 seconds. Thus far I've only flown these Micro Maxx motors in negligible winds, so I don't know how it would fare in windy conditions -- probably not too pretty. But under the right conditions (no wind, no launcher drag), it looks like these motors can loft small 1/4A models (ie: certainly not models that a 1/4A can barely lift). I've got a 10.5mm Mini-Dactyl and a Bumble Bee-like B/G that are each about 6.5 grams empty that might fly acceptably on these motors (time will tell).
I'm moved to make some comments here on the concept of "backyard rocketry" (or even "indoor rocketry", as Bob Kaplow advocates). Early in my flying career I had a fairly large field within walking distance and it was invaluable in my being able to test new designs. I no longer have that available, and find myself in a similar situation with many people. If you want to test a new model, you need to pack up the car and drive to a however-distant field (which may not be available when you want to use it or the weather may have changed...).
With these little models I'm rediscovering the joy of building something, looking out the window to see if the weather is acceptable, then grabbing a handful of gear and just doing it. From impulse to expending impulse in mere minutes. I've gotten into the habit of working on these models after dinner, so by the time I'm ready to fly it's near sunset and winds are minimal. My backyard is hardly perfect (maybe 75 feet square with an adjoining area if the breeze is right), and some of these super-light models will really test it (if I get that B/G working), but at least I have a chance of flying and recovering these models here. And, in the case of my SD model hanging in the tree tonight, I have only to look out the window (versus a one hour drive to our usual field) to see if it's ready to come down yet.
Indoor rocketry, while a neat idea, has the barrier of not always having a building with a 50 or 100 foot or higher ceiling available. On the other hand, thinking of the Quest wind speed recommendations (5 to 7 mph or less), a suitable indoor facility might be just the ticket for competitions. You could practice in your backyard, then go to the more or less controlled conditions of your indoor facility for your contest. No more rain-outs, wind-outs, snow-outs... (so long as you can still get to the "hangar").
One interesting aspect of indoor flying would be keeping it under the ceiling (a much more literal term than the FAA usage :). These models show a tremendous dependence between launch mass and altitude performance, so it would be quite easy to set a minimum launch mass compatible with your indoor facility and announce it with your sanction: "we'll be flying 1/8A B/G Indoor and 1/8A PD Indoor with a minimum launch mass of 7 grams"...
On the Quest wind recommendations, I think it is in keeping with the heavy models they provide and the short launch rod length they give you to fly it off of. (With the reports of marginally or just plain un-stable flights on RMR, I wonder how many are the result of these factors.) I think a high-performance 1/8A contest model (ie: not underpowered) would probably be flyable up to the NAR limits, but I won't be sure until I try it.
Nine days in, eight motors consumed, eight motors to go. Sounds like I better find myself a fix sometime next week... :)
BTW, the Toys R Us where I bought my starter kits still had the same four remaining kits on the shelf today (and no new motors). Not quite selling like hot-cakes. :(
Some days, everything just goes right...
We had some good thunder and winds in the early morning hours, but not enough to dislodge my SD model. A good excuse to build a replacement.
I wanted to take a slightly different tack, moving the body size up one more notch to Apogee T-10 / Totally Tubular T-4. First, to diversify my testing, second to give me more room to carry a parachute (a mylar streamer may fit well into the 0.35" ID T-3, but opening a 'chute out of that is a whole 'nother story).
The model was built from an Apogee 10.5mm balsa nose cone, a five inch piece of T-10/T-4, and two TT 2-4 centering rings (installed as in the other model). Fins were hard 1/32" balsa with a root of 0.75", a tip of 0.375", and a semi-span of 0.875". Shock cord was ~18 inches of 15 pound kevlar. I drilled out the 3/32" Plastruct tubing with a 1/16" drill bit and it made very good launch luglets with no binding (2x 1/8"). The parachute was a 13" 'chute made of thin "Canadian red" plastic, with eight shroud lines. Empty model mass was 2.5 grams, 'chute only was 1.2 grams, and total lift-off mass was 5.4 grams (with approx. 1/2 gram of tape and wadding). It looked like a slightly enlarged version of the lost SD model.
The 'chute was folded into a 45 degree section, folded twice from the tip (so it was about 2" high), then scrunched (not rolled) into a package that would fit into the T-4. The trick is to make all necessary folds in opposite directions and to avoid folding when you can (the more nested folds you have, the less likely they are to unfold with a lightweight model and a low-velocity deployment). It actually fit pretty well into the tube once you put your mind to it. The 'chute was placed into the tube (after about 3/4 of a piece of Estes wadding, in several pieces) and the shroud lines were wrapped around a pen placed into the tube, then slid into the tube. Then the shock cord and nose cone are placed into the model.
The model was launched using all-Quest equipment (rod, ignitor, controller). The nominal 0.43" tube diameter was a good match with the #1 rod position on the Quest launcher. The launch was good with just a little tip-off. Altitude approximately 100 feet. Ejection was right about at apogee. Deployment was pretty good, quick with just a little welding. And then it hung. And hung. :) Flight time was 39.6 seconds, right on target. I believe that the flight was not thermal-aided. Drift during the flight was less than 50 feet. It is really neat to fly a PD model that you actually have a shot at getting back. :)
Using all pre-manufactured parts this time (tube, nose, rings, existing 'chute), I was able to go from building in my basement, to prepping, to flying and recovering the model in less than one and a half hours. Backyard rocketry rules! :)
Prodded by some discussion of Micro Maxx R/Gs on RMR, after dinner I put some time into an auto-elevator model. For the uninitiated, an auto-elevator R/G is a glider that has a movable elevator that is in one position for a straight rocket boost and changes to a second position (burns string, rubber band pulls, etc...) for a stable glide recovery. My reasoning is that other more common systems (slide wing, slide pod) are easier and more reliable, but they carry a notable weight penalty for the mechanism. With their limited lifting capacity, that would kill any performance from a Micro Maxx R/G. The auto-elevator system is just about the lightest and simplest to implement.
The wing I used was one that I had built several (OK, 15 or so) years ago. It was a nice 1/32" C-grain balsa with a lightly-CA'ed finish, but it was so light I was afraid that it wouldn't stand up to the smallest motors available at the time (Estes 1/2A3T), so I hadn't used it. It was about 19 square inches and weighed under 2 grams.
I used a hard 1/16" balsa fuselage (beefed up a bit over my usual to withstand any stress from the auto-elevator mechanism). and light 1/32" balsa for the tail feathers. The up-sized T-2 I used for the first glider had been a bit troublesome (a tight fit and misalignment), so I downsized a T-3 for this one. I slit the tube, placed it over a T-2 for sizing, overlapped it about 1/4 turn, and CA'ed it together. The external "step" was butted against the side of the pylon, providing positive alignment and more contact area for gluing. Since the pod didn't have to be gas-tight, the internal "step" was not a liability. The nose was a crude hand-carved balsa one. Two 1/8" diameter luglets under the wing were used for launch guidance. A small tab of 1/32" thick lead (about 1/2 gram) on the pylon was used to trim the CG. The empty weight was 4.75 grams. And this model positively dwarfed my other Micro Maxx B/G. :)
The auto-elevator system was minimal. Only the leading 3/4 of the stabilizer was attached to the fuselage. There was no elevator hinge, the thin balsa's flexibility was sufficient. A thin line was attached to the top of the stabilizer trailing edge, routed through 3/32" Plastruct luglets on the tail (to give a downward pull on the elevator, as an alternative to a conventional control horn) and fuselage, with a loop at the front. For prepping, a light thread was passed through the loop, and both ends of this thread were threaded through ejection vents in the tube and taped down. (ChAD tip: a handy threading tool can be made from half of a used Solar ignitor, just bend a loop into the end. Just the thing for on-field threading emergencies.) There was no rubber or other method to activate the elevator, as it seemed that the natural springiness of the balsa was sufficient.
OK, so shortly before sunset the model is built, a few hand tosses to check the trim (looks nice), it's prepped and ready to go! For a launcher, I used an Estes pad, one 18" launch rod, and a basswood spar (mounted in the hole for the 3/16" launch rod) to act as a gantry. I attached a Quest Micro Maxx ignitor to the gantry with a clothespin and used an Estes launch controller for ignition.
The model is launched... and all my bad auto-elevator and no-moving-parts R/G memories come back. The model completed one inside loop (pitching up, about 25 foot radius) transitioned horizontal at about 15 feet in the air, and made a short glide. Flight time was 5.4 seconds.
Hmmm, needs a bit more down elevator for the boost... It sure would be a shame to spend this time building and not know how it works... It was starting to get dark, but I raced inside. I sliced the rudder to allow the elevator to go down further on boost and re-prepped it. Eleven minutes later we were ready to roll again. Another launch... and this time two outside loops (pitching down, about 15 foot radius). Hmmm, maybe not quite that much down elevator... :) The model again ejected near-horizontal, but dove to the ground this time. With the greater elevator throw, I think it wasn't able to flex back fully to the glide position. Flight time was 3.0 seconds. (Dang! Things sure happen fast with these little critters.)
It was dark, so no more flying was possible. Later, a few mods were made to the model. The first flight had about 1/16" or 2/32" of elevator travel (equals one inside loop). The second flight had about 5/32" of travel (equals two outside loops). I think the sweet spot is about 3/32" for this design, so a 1/16" shim was put on the bottom of the elevator (where it rested on the rudder) to achieve this. Also:
I was impressed by the boost distance traveled by the glider (if not the vertical altitude achieved so far :), so I think further test flights will be on the ASTRE launch range. Gliders, with their (sometimes unpredictable) circling path and with the greater time investment involved, are just a bit too much of a risk with my limited space.
Finally, I think I will use a full 36" (or longer) launch rod for further flights of this model. I think the half rod was sufficient for the model to get enough airspeed to stabilize it. My main rationale is to keep the model on the rod for as long as possible, hopefully through the thrust spike, to minimize any pitch-inducing thrust.
Tonight we planned to have an ASTRE meeting at my house, with some Micro Maxx demos, so I wanted to get some more motors. I called the (more distant) Clifton Park Toys R Us, but they had no motors. So I stopped by the Colonie store. No motors in sight, but one more starter kit satisfied my needs. Also, one of the starter kits had been sold to some lucky Micro Maxx'er in the Capital District (no one in our club, though).
Here's a summary of the specs of the Micro Maxx models that I have collected so far:
| Model | Diameter | Length | Mass | Recovery |
|---|---|---|---|---|
| Spacefighter | 0.55" | 4.38" | 8.3 gm | conv. streamer |
| UFO | 2.75" | --- | 7.7 gm | featherweight |
| Saturn V | 0.50" | 5.8" | 6.5 gm | piston streamer |
| Space Shuttle | 2.0" (span) | 3.5" | 9.1 gm | conv. streamer |
| Tomahawk | 0.41" | 3.9" | 5.8 gm | piston streamer |
| SR-71 Blackbird | 2.3" (span) | 4.8" | 8.8 gm | piston streamer |
We had our meeting "on location", moving the folding table and chairs out of our basement lair and into my backyard. Weather was absolutely perfect for flying: temperature in the 70s, a high overcast, and virtually no wind. Ed Eades, Eric Schadow, Mark Hutchinson, and Chuck Weiss watched the demos. After showing the models, motors, and launcher, we got down to business.
The Quest launch controller and pad was used for all flights unless otherwise specified. When the first model was ready to go, it had continuity, but the launcher didn't have the poop to light the ignitor. Someone on RMR suggested cleaning the internal ignitor contacts (they eventually get coated with motor exhaust) with the launch rod. This worked well for me. Tom Binford on RMR also suggested using a NiCad 9v battery (it has 3x the current of an alkaline) and charging between flying sessions.
First up was the Saturn V. For my money, this is one of the cutest and most desirable of the Micro Maxx models. Lift-off was good, but early in flight it started to cone, getting progressively worse, and probably only reaching 40 feet altitude. The streamer did not deploy and the Saturn made a very reasonable facsimile of a (lawn) dart. Scratch three astronauts. :( Someone on RMR suggested a bit of noseweight (for stability) and cutting the streamer length (to aid deployment). Ted Cochran has suggested vectored thrust from nozzle degradation for the late-flight instability, but I'm not seeing that on any of my scratchbuilt models. With a bit of work, this could make a nice flying model yet...
The next flight was the Tomahawk Cruise Missile. I don't know if it was do to its asymmetrical construction (jet air intake), but its trajectory veered about 20 degrees from the vertical, towards my house. That took its downward path through a small maple tree, and we looked on as it bounced its way to the ground. Altitude was about 70 feet, probably due to the lighter weight of this model. The recovery piston deployed, but the streamer did not unfurl. It seems that a flaw of this design is that the streamer is free to catch the outer tube wall and streamer telescopes as the piston deploys, trapping the outer edge of the streamer and preventing deployment. A possible fix could be a second piston mounted directly below the streamer that would make sure that the streamer did not telescope and was free to deploy. Hard to retro-fit, though. We debated the merits of "plausible deniability streamer recovery" ("we're sorry the model bonked you on the head, but we did install our patented piston-streamer for recovery purposes...").
I felt like doing some real flying, so I prepped my T-4 PD model. I showed the guys my motor taping system and the packing of the 'chute into a tiny space. The model boosted nicely to 100 feet or so, vigorously popped out its 'chute, which deployed nicely, and drifted down. The weather was calm, not much of any thermal activity (although the model did hit little currents and bubbles on the way down). It drifted about 100 feet away with a flight time of 36.5 seconds. One of the neatest things about flights like this is that the model is at a low enough altitude and descends slowly enough that you can see everything happening (a bit like B Eggloft or 1/4A Parachute Duration, only more so).
I felt like a contrast, so the next flight was the UFO. This flight actually went off better than my first, with the UFO reaching perhaps 15 feet and the ejection charge going off well before landing. Granted, it is a dopey-flying model, but it is different. When I look at all of the Micro Maxx I've got, it's the only one that has flown twice, owing to the fact that it is so totally different from the others (even if such an impulse-eating design is really dumb for such low power motors).
I was looking at the selection of unflown models, and ended up going with the Space Shuttle. It has a conventional streamer, so I added a bit of Estes wadding. The boost was fairly good (to 50 feet or so, with a very slight arc), but the ejection charge failed to deploy anything and the model plummeted to the ground, nearly bopping my father on the head. Scratch some more astronauts... The fit of the nose was a bit tight, but I didn't think it was that tight. :( I'll have to check that before flying it again. The Shuttle also has an internal ducting system, and an area where the shock cord is mounted which allows the ejection charge to vent. It looks like these models are more designed to be loose-fitting and gas-venting, versus the typical model rocket dictum of a snug fit and vigilance against gas leaks. Perhaps with the design constraint of tight spaces (both for fitting a recovery device and possible over-pressurization), this is the only way to go, thus the nose fit should be looser.
OK, it was getting late, I was running low on motors (at this point I had used up my first two starter sets' quota), but I wanted a better finish than that. I had been meaning to fly my tiny B/G again, but had planned to do it at our main flying field, due to its excessive performance. Then again, I had a willing recovery crew, so it was a good opportunity. I hemmed and hawed, I warned the guys that this was going to go "very high, very fast, and very far" compared to what we had seen thus far, and then I let myself get talked into it. :)
I set up the B/G on the Quest pad, on a table tilted about eight degrees pitch down, to compensate slightly for its boost characteristics (I still wanted some pitch up, to get it into a more favorable recovery area). Power was from an Estes 6v launch controller, to a Quest ignitor. The model took off like a scared cat, pitching up and back a little as expected, probably at 100 feet or so altitude. The ejection charge blew the motor out, the fuselage held up this time, and it started gliding! It was a rapidly shrinking spec, making a bee-line for a nearby garage, apartment building, and massive tree line. It turned a little and, all to soon, vanished near the roof line. Ed Eades managed to time it for 26.3 seconds to that point. Our recovery crew headed out, and Mark Hutchinson quickly found the model, on the front side of the apartment building, behind some shrubbery. It looks like it may have hit (or been aerodynamically affected by) the building near the roof line, then rapidly (and unexpectedly) descended, which is why we didn't see the end of its flight. It was recovered with little damage, although the stabilizer showed a small dent where the engine casing grazed it.
As you might guess, this successful flight and recovery really made this meeting!
While catching up on this log, I was reminded of these old posts while searching RMR. I hope that this will not have an adverse effect on the future of the Micro Maxx line, but I have trouble seeing it any other way (I don't know what other "real rocket guys" Quest has to draw upon). :(
======== Subject: Bill Stine leaves Quest? From: bobsanford1@my-deja.com (Bob Sanford) Date: Thu, 01 Jul 1999 17:23:12 GMT I just learned about a press release noting that Bill Stine is leaving Quest. Today, Thursday, is his last day. No further details are provided. ======== Subject: Re: Bill Stine leaves Quest? From: !70156.625@no.spam.compuserve.com! (Mark B. Bundick) Date: Sat, 03 Jul 1999 12:59:55 GMT Bill is leaving to pursue the creation of a model rocket museum in AZ. ========
We should have been flying our open meet/Apollo 11 commemoration today but due to the excessive heat (93 degrees, dewpoint 70 degrees -- maybe not much for some of you, but plenty for upstate New York!), we postponed. Which gives me some more time to work on this.
A while back I had proposed that the NAR Contest Board create events for these new motors. Currently they are Contest Certified and they can be flown at contests, but only in 1/4A events (at a significant impulse disadvantage) or as special effects motors for craftsmanship entries. Two things would have to be done: first, a new class for 1/8A motors (0.0 - 0.3125 Nsec) would have to be created (and 1/4A would bottom out at 0.3126 Nsec). Second, existing events would be expanded to 1/8A classes. I made these specific suggestions to National Contest Board Chairman Tom Lyon (from an email January 12, 1999):
> I would say official. Provisional events are usually new events that >need to have their rules tested and tweaked. For the 1/8As, I don't >foresee any events specific to them at this point, but an extension of >existing event rules down one more engine class. I'd advise... > >Event WF Comments >1/8A Alt 9 >1/8A SR Alt 13 12.5 - 25 cm (5-10") >1/8A x2 Cl Alt 12 >1/8A PD 7 40 sec max >1/8A SD 8 20 sec max >1/8A HD 21 20 sec max >1/8A SR Dur 12 12.5 - 25 cm (5-10") >1/8A B/G 19 30 sec max >1/8A R/G 21 30 sec max >1/8A FW 19 30 sec max >1/8A Sc Alt 25 > > WF are based on whether the event would be easier, harder, >or relatively unchanged from the 1/4A version. > > Max's should be flight tested, if time permits, but I think the >two thirds of 1/4A max's is a good target. One half would be >too easy, IMO.
My flight testing, as you may have noted, has been geared towards testing some of these events. On July 4, I sent this email to members of the Contest Board:
> I've finally gotten some of the Quest Micro Maxx product and >have been doing some contest model testing. Thus far, I would >say the engines are viable contest motors and deserve their own >1/8A contest event classes. Models can be scratchbuilt specifically >for the Quest motors or *small* 1/4A models can be adapted (I >would say most models that have an empty mass of 7 grams or >less [1/4 ounce] could make qualifiable flights with the Micro Maxx >motors -- see the 6 gram HD flight below). > > My flights thus far: >Event Size Recovery Result >1/8A B/G 4" span --- broke at ejection, no glide, 7 sec >1/8A B/G 4" span --- broke at ejection, no glide, 25 sec >1/8A SD 0.38" dia 2.5x26" str no deploy, 9 sec >1/8A SD 0.38" dia 2.5x26" str 22 sec >1/8A SD 0.38" dia 2.5x26" str 17 sec (caught 40' in tree) >1/8A HD 0.43" dia 6" Roseroc 8 sec >1/8A PD 0.43" dia 13" 'chute 40 sec > > Much more extensive details in the log available at: >http://www.acmenet.net/~jvincent/qmm-log.txt > > In January I wrote to Tom Lyon with the following event >suggestions: > ***quoted above -- clipped*** > > Based on testing thus far, I stand by those recommendations. >The short delay (1 sec) may be a problem in optimized altitude >models, but I haven't tested that yet (and it hasn't been a problem >with non-optimal models).
Tom Lyon is soliciting comments on the creation of these events. Please contact him at ZOG43Lyon@aol.com with your comments, pro or con. He also plans to discuss the creation of these events at the Competitors Forum at NARAM-41. Right now, the biggest hurdle seems to be commercial availability of the motors, both in the short and long term (so go buy some more!).
I stopped into the local Toys R Us and found it was my lucky day -- they had Micro Maxx motor packs. I promptly cleaned them out, six packs worth. Now, Pinky, we can rule the world!...
I wanted to work on the Quest Saturn V. It's a cute little thing, and it would be immensely cuter if it would fly straight. However, it seems to exhibit a coning motion at and after burnout. This can be barely noticeable or quite severe, almost to the point of being just plain unstable. Ted Cochran has suggested nozzle erosion, but I think its stability (since I haven't seen the effect in scratchbuilt models).
Earlier in the day I built a clear plastic fin unit for the Saturn. It was a ring made from a 0.005" x 0.5" x 3.0" piece of clear acetate, with four equally spaced 1/8" notches to locate the unit on the leading edge of the existing fins.
I took a nap, got up late, and then was rushed doing my flights, which led to some poor rocket science. :( All flights were made in minimal wind at twilight. The first flight was a control flight of the stock model. Center of gravity was located right around the ejection ports. I also tried Ted's suggestion of accordion folding the streamer instead of rolling it around the internal piston. This flight had a mild coning during coast, but a decent flight to 50 feet or so. The streamer ejected properly and the flight was mostly successful (the best flight of the night, ironically enough).
The second flight was with the clear plastic fin unit. The CG was in the same position as the stock model. Here I made my mistake, by allowing the fin unit to just sit over the fins. It was snug enough to invert the model with it staying in place. However, it was not snug enough to resist the aerodynamic forces of flight. This resulted in an unstable flight, as the fin unit apparently shifted when the model assumed an angle of attack. Further, the streamer was too tight and did not eject on this flight. (Yes, Ted did recommend cutting the streamer length, but I didn't want to do that if I didn't have to. With the streamer folded and placed on one side of the piston shaft, it tends to bind a bit, so you really do need to trim the streamer. :)
I want to take another stab at the clear plastic fin unit, with a more rigid mounting. I had originally considered mounting it to a thin waferglass plate captured between the model and the engine retainer, but the fin ring seemed like such a good idea at the time... :)
I took the model downstairs and attacked it, attempting to add noseweight. Unfortunately, there isn't much room to do so. Another RMR'er had reported replacing the escape tower with metal, but I rejected that for safety reasons (particularly after observing the non-deployment flight profile). By firmly grasping the piston shaft and twisting the CSM/LM assembly, I was able to free the assembly (by fatiguing and breaking the plastic inside the nose, but not the piston shaft). I ground this area out with a Dremel tool, and placed some small pieces of lead in the assembly, reattaching the assembly with CA glue. The modification added approximately one half gram to the model's mass and moved the CG forward about 0.2".
The flight results were not significantly different from the control flight -- a little bit of wobble and coning. The streamer failed to deploy again.
So, what did I learn? Not much. Don't fly when half awake or too close to dark? :) I learned nothing conclusive from the CG shift and the plastic fin unit (as implemented) was a waste of hundreds of milli-Newton-seconds. Have to work on this some more...
Doing some catching up here. Over the past few weeks I've had some other things going on which have kept me from "the quest". :) The lackluster Saturn results weren't exactly worth writing home about either. I hope to get back to flying these little guys and documenting it here. Also, I'd like to get some plans drawn up for the models already discussed.
Another thing which I've added to these pages is a conversation from rec.model.rockets about the Czech micro motors, appended to the Czech motor specs and background page. The unfortunate news is that these little Czech motors are no longer being manufactured.